This invention relates generally to the field of systems, instrumentation and methodology for the fixation of vertebrae relative to each other, and more particularly relates to such systems, instrumentation and methodology that utilize pedicle screws affixed to vertebral pedicles and one or more rods that rigidly join the pedicle screws of plural vertebrae. The invention contemplates the combination and use of plural pedicle screws, one or more rods and means to optimize insertion of the rod into the pedicle screws, such means comprising a guide cable and instrumentation to position the guide cable in the pedicle screws, whereby the screws are implanted into the vertebrae, the guide cable positioned in the screws and the rod subsequently guided into the pedicle screws along the guide cable, all using minimally invasive surgical incisions. With regard to instrumentation of the invention, the invention relates to guide cable threading or advancing devices adapted to pass the guide cable from one pedicle screw to an adjacent pedicle screw.
Early surgical techniques for affixing rods to vertebrae entailed relatively long incisions to provide access to the vertebrae. Newer techniques utilize multiple percutaneous stab incisions at chosen locations rather than a single long incision. Such techniques are often referred to as minimally invasive surgery (MIS). The MIS techniques are preferable with regard to recovery time.
One advanced MIS technique provides for the placement and passing of a guide cable or wire between the pedicle screws such that the guide cable can be utilized to direct and/or pull a fixation rod into proper position spanning the pedicle screws. Inserting the guide cable into the first pedicle screw tower and then through the tissue between the pedicle screws can be a difficult and time-consuming task. It is an object of this invention therefore to provide structure for a pedicle screw tower that greatly reduces the difficulty in this task.